Electrical switch for thermostats, etc.



Sept. 16, 1930. .1.A. SPENCER -ELECTRICAL SWITCH FOR THERMOSTATS, ETC

Original Fil'ed Aug. 9, 1923 F46 closed position;

Patented sept. 1s, 1930 UNITED STATES PATENT oPEicE .TCHN A. SPENCER, oENEwToN, MASSACHUSETTS, ASSIGNon To `arrarclin TnnxosTAT CoMPANY, or CAMBRIDGE, MASSACHUSETTS, A CORPORATION or MASSACHUSETTS ELECTRICAL SWITCH FOR THERHOSTATS, ETC.

Application illed August 9, 1923, Serial No. 656,528. Renewed June 7, 1988.

Objects of the present invention are to provide an electrical switch which will satisfactorily interrupt a substantial current with little or no sparking, which will insure positive completion of the current at the points of interruption thereof aswell as positive4 and simultaneous interruption of the current, which will positively retain the circuit completingmembers in proper circuit closing position which may be readily adjusted to control t ie operation of the current breaking mechanism, and which shall be extremely compact in form and occupy minimum space proportionate to the current controlled thereby. e In one aspect the invention comprises mechanism for .simultaneously breaking a circuit at a suflicient number of points in series to keep the potential substantially Within the non-arcing lrange for the material constituting the contacts,` and separate and independent means for actuating the contact members into operative position and into inoperative position, inl-this respect distinguishing from copehding. application 627,855, filed March 26, 1923. Other aspects of the invention will be evident from the following description and claims.

The invention accordingly comprises th elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structure hereinafter describe and the scope of the application of which 'will'be indicated in the following claims. l

To assist in underst'andingvthe invention, one-concrete embodiment is shown in the accompanying drawings in whichzig. 1 is a sectional view ofa supporting mem er with the improved switch applied v thereto; t v Fig 2 is a rear view of the switchmechamsm removed, being taken on line 2-2 of' ig. 3 is a front view with coverv removed; 4 is a sectional view on the line 4-"4 1g of 3 showing theswitch elements in Fig. "5 is a similar view illustrating 'the separation of the switch elements;-and,

Fig.` 6 is a detailed sectional view on the line 6-6 of Fig. 3.

The particular embodiment of the invention chosen for the purpose of .illustration comprises a base block 10 bearing a plurality of spaced stationary switch elements 11,

held by fasteners 16, and separated by gaps 17, and a plurality of movable switch elements 12. vIndependent actuatingA means such as springs 13 serve to press the several elements 12 against the spaced elements 11 to complete the circuit therebetween, while a sutiable actuating means is employed for shifting the movable switch elements into inoperative position. This actuating means is preferably independent of the means for moving the `elements 12 into operative position and may be either a mechanical, manually operable mechanism or an automatic device such as the cupped thermostatic` disc 14 shown in the drawings.

In the particular embodiment illustrated the device is shown as applied to a heated` element 15 to automatically regulate the heating thereof through the electrical circuit 16, 17 which may be connected directly in the heating circuit in case of electrical heating or indirectly throu h a control circuit in case of gas, coal or e ectrical heating.

The switch elements 12 are shown in the form of discs 12 mounted on the ends of guides or plungers 18 which are slidable through apertures 19 in block 10. f Theguides have enlarged portions providing shoulders 20. Springs 13 in pockets in theI base 10. bear at one end against the base and at the other against the shoulders 20 to l actuate the Same to hold the dis cs normally in tight engagement with the plates 11- at olpposite si es thereof, vthus com leting thg e ectrical circuit. Beyond shoul ers 20 the .guides'are provided with socketed portions A21 receivin .mounting nonconducting blocks 22. By t e switch elements 12 loosely 'upungers 18 the elements may turn on the plungers and thereb equalize the wear.`

Binding posts 23 an 24 .carried by the. base adjacent the circular row of contacts serve tovconnect' currentleads 16 and 17 with conductor fingers 25 and 26 which lcontact on the p with the adjacent discs 12 respectively. The complete electrical circuit through the switch is from one of the terminals 16 or 17 through its conducting linger, thence 5 through the alternate contact discs and plates to the otherv contacting nger, and out through the second terminal.

In the particular form illustrated siX discs or connector plates 12 are illustrated.` It

m will be. understood that when the members 12 are simultaneously shifted out of engagement with the plates 11, the current is interrupted at each side of each disc 12 so that in. this particular form the current is simult taneously interrupted at twelve dierent points in series. Experiments have shown that with a switch no larger than that illustrated in the drawings a 500 volt ampere current may be interrupted without substantial areing.

To insure best contact surfaces and conduction effects the several parts '12 and 13 are preferably of bi-metallic form, having a heavy body portion 12a (Figp) of copper orsuitable conducting material and a face portion 12b of silver or other good contact material, preferably a material having a high critical ar'cing voltage, thereby to minimize arcing.

Carried centrally by the base 10 is a bushing 27 having head 28 and nut 29- bearing against opposite faces ofbase 10 to secure the bushing in position. This bushing is interiorly threaded lfor engagement with post 30 supporting a cupped thermostatic disc 14, the threaded engagement permitting adjustment of the disc relative to the bushing and tothe projecting contacts 22 of the switch members. Lock screw 31 serves to secure threaded post 30 in adjustedposition. Guide members 32 may be adjustably engaged vin the base, these members being loosely received within apertures 33 of the disc,thus holding `it against angular displacement and guiding it in its snapping action.-

The action of cupped Athermostatic discs is well known and is particularly described `and claimed in Patent-1,448,240, dated March 5 13, 1923. They are ordinarily formed of bimetallic material in concave, convex or en ped form, and under -normal temperature w11 be cupped in one direction and when heated above a predetermined temperature,

due to difference in the coetlicients of expanv if sion of the materials of which they are com'- posed, will suddenly change shape or reverse heir concavo-convexityas indicated in Figs. f4 and 5 of the drawings. It is to be underm stood that while this particular mechanism for controlling movement of the discs 12 is here illustrated and described vother mecha- V 4nism 'for producing an equivalent result either automatically or otherwise may be emu ployed for actuating the switch elements 12 ytiplicity of points by shifting 'discs 12 away without departing from the spirit of the present invention in its broad aspect.

In operation the thermostatic disc will normally be in the shape shown in Fig. 4 or out of engagement with contacts 22. Springs 0 13 on individual controls for the several 7 `discs 12 then hold the discsin tight circuitclosing engagement with the adjacent plates 11. When the temperature rises above a p redetermined amount thel disc 14 will snap to the position shown in Fig. 5, automatically engagingthe several contacts 2 2 and pressing the guides 1S through base plate 10 and thus simultaneously breaking the circuit at a mulfrom plates l1 against the pressure of the 80 independent actuating means therefor. W'hen the temperature again drops to a predetermined value the disc 14 will snap in the reverse direction and thereby permit the vdiscs 12 again to close circuit.

' It will be seen from the above that the discv 14 is operatively associated with, but not connected to the contact assemblies such as shown in Fig. (5. When the switch' is opened it touches these assemblies but it is not con- .nected to them in the sense that it is linked .or fastened thereto.

It should be understood that the present invention is not limited to any 'particular combination of materials having different thermal. ooetl'icients of expansion but is intended to embrace in its scope any combination of materials having dissimilar coefficients of expansion sufficient to causethe characteristic reversal of curvature. Fur ther-more, the materials comprising the composite thermostatic sheet may be secured together in any desired manner by riveting, soldering,- brazing or otherwise, although it is preferred to unite the materials comprising the sheet by welding or similar means to secure a substantially indivisible sheet.

In view of the above, it will be seen that the several objects of the invention are achieved and `other advantageous results attained.

As many changes could be made Tin carrying out the above construction without departingfrom the scope ofthe invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim: Y'

1. A switch comprising relatively movable contacts, means for yieldingly holding said contacts in interengagement, and a hi-metallic, snap-action thermostatie device unconnected to said contacts but arranged to disengage the contacts in its snap action at a variable predetermined temperature.

'2. A switch comprising an annular series of relatively movable contacts, means for yield-ingly holding the contacts iii-interengagex'nent, and a bilmetallic, snap-action 13o thermostatic disc mounted atthe center of said annular series, the, disc b eing unconnected to said contacts, but arranged to clis-4 engage the contacts in its snap action.

' 3. An electrical switch comprising a plurality of stationary contacts, a plurality of contacts movableinto and out of Contact with said stationarycontacts, and a temperature responsive device including a cupped sheet having a peripheral portion free to snap back and forth, said movable contacts being operativel associated with but not connected to said dsevice to move when said sheet snaps.

4. A switch comprising a base, a plurality of fixed spaced contacts carried` by the base, resiliently actuated contacts for closing the spaces between the fixed contacts, and means comprising a bi-metallic, snap-action thermostat, :for shifting at predetermined tempera'- tures the resiliently actuated contacts in 0pposition to the action of the resilient actuating means. f 7 5.` An electrical switch comprising a member carrying ,a stationary set of contacts spaced from each other in an annular row and c a movable set of contacts disposed in an annular row to bridge certain of the spaces between the contacts of the other set whereby a .circuit connected to spaced contacts maybe broken simultaneously in a plurality of points in/series by disengaging said sets from each other, means carried by said member and movable longitudinally of the axis of said an- K gagement and bi-.metallic thermostatic meansv nular rowfor shifting the movable contacts into. circuit closing,- position, other means carried by said member for shifting the movable contacts to interruptthe circult, and means for controlling the JI.action of said last means. 6. Anelectrical switch comprising a base, a series of contact plates spaced in a row on the vbase, the base having guide apertures therein intermediate .adj acent I plates, guides slidablein the apertures, circuit closing members carried bythe guides and adapted to bridge the spaces"j,between' adjacen 4fplates, and' thermostatic `'ineans comme o said guides or actuating said members.

7. An electrical switch comprising a. base, a series of contact plates spaced in a row on the base, guide apertures in the said basefin-V termediate adjacent contact plates, guides slidable inthe apertures, circuit closing members ycarried by the guides and `adapted to means *for actuating the guides to hold the plates andcircuit closing members 1n encommon to said guides for separating said plates and members.

8. An electrical switchccomprising abuse, a series of` contact plates spaced in a row on thebase, guide-apertures in said base intermediate adjacent plates, guides slidable 4in the apertures, circuit closing members carried by `the guides and adapted to bridge the f the base,

bridge the spacesbetween adjacent plates,`

spaces between adjacentplates, yielding means for actuating the individual guides to" hold the circuit closin members and plates in engagement, and b1-metal1ic thermostatic 'mean-s common to the guides for suddenly separating the members and plates against the action ofF said yielding means at substantially predetermined temperatures.

9. An electricalswitch comprising a-base, a series of contact plates s aced in a row on the base, guide apertures 1n said base inter-` mediate adjacent plates, guides slidable in the apertures, circuit closing members car-` ried by the guides and adapted to bridge the. 'spaces between adjacent plates, means for actuating the individual guides to yieldingly hold thelbridging members and plates in vcir-` cuit closing engagement, and a bi-metallic thermostat for simultaneously shifting the several guides to move the bridging members into inoperative position. l j 10. An electrical switch comprising a base, a series of lcontact plates spaced in a row on guide apertures in said base, intermediate adjacent'plates, guides slidable in the eoI apertures, circuit closing members carried tact members mounted on` one face thereof; a plurality of co-operating movable contactv bridging members supported and guided by the contact table, resilient vmeans for nora mally yieldingly holding the bridging members in operative engagement with the fixed contact members, and a snap'acting element for effecting sudden'and substantially simultaneous movement of said by impact therewith.

bridging members ilo 12. Athermostatic controlcompri/sing a cupped disc, a base, means for-supporting the` rcenter .of said disc on said base, and 'means symmetrically located with respect to the center of said disc for guiding the peripheral portion of said disc when said disc changes shape in response to temperaturevariations.

,13. A` thermostatic control lcomprising a cupped disc having aplurality of apertures `in the peripheral portion thereof, a base,

means .for supporting the center of said discz.

Ion said base, guide-members passin throug the holes in said disc, and adjustab y securedl to said base. i

14. A thermostatic control comprising a` cupped disc, said disc having a plurality otV apertures in the peripheral portion thereof,V u bue, means for supporting the center of" 4- s l, -l'nvaoia saiddisc on said base, and screws' assinig through the apertures of said disc and e gaging the base. l

15. A thermostatic control comprsing a 5i member adapted to snap back and orth suddenly in response to heatvstrains, a base, means for supporting said member on said base, said member having a plurality of holes therethrough, screws passing through said.4 holes and engaging said base.

16. A thermostatic control comprising a c cupped disc 4having a plurality of holes in the peripheral portlon thereof, a base, means for adjustably supporting the center o said. 5 disc on said base, and a plurality of members assing through the holes of said disc and ad- ]ustably engaging said base. Y

17. thermostatic switch comprising a l cupped disc having peripherally disposed 20 apertures, a base., means for supporting the center of said disc on said base, electrical..`

switching'mechanism in operative relationship to `said disc and screws passing through lie apertures of said disc and engaging the g5 ase.

18. A thermostatic switch comprising a cupped disc having peripherally disposed apertures therethrough, a base,`means for adjustably supporting the center of said disc on said base, electrical switching means in operative relationship to said disc, and screws passing through said apertures and engaging said base.

19. An electrical switch comprising a plurality of contacts, a second plurality of contacts movable into and out of contact with the first-named plurality of contacts, and a temperature responsive device includingacupped lsheet having aperipheral portion free to 4G snap back and forth, said device being'op' eratively associated With -but not connected to vone set of contacts and adapted to move the other plurality of contacts `when said sheet snaps. I

w Signed by me at Cambridge, Massachusetts,

this-6th day ofAugust, 1923.

" JOHN A. SPENCER. 

